US3635286A

US3635286A - Storage tank for liquid metal

Info

Publication number: US3635286A
Application number: US888369A
Authority: US
Inventors: Frantisek Dubsek; Vaclav Tomes; Mojmir Nigrin; Jiri Sobotka
Original assignee: Prvni Brnenska Strojirna Zavody Klementa Gottwalda
Current assignee: Prvni Brnenska Strojirna Zavody Klementa Gottwalda
Priority date: 1969-12-29
Filing date: 1969-12-29
Publication date: 1972-01-18
Anticipated expiration: 1989-01-18

Abstract

A system for circulating heated liquid metal (e.g. metallic sodium) through a conduit arrangement wherein, for example, the liquid metal functions as a heat-exchanging medium and is alternately cooled and heated. The system includes a unitary liquid metal storing and circulating device having a tank for storing the liquid metal and a pump for circulating the liquid. The pump, which is immersed in the liquid in the tank, has a liquid flow-through bearing and means for removing excess liquid metal which flows through the bearing. Valves associated with the system have liquid metal flow-through seals; means is provided for removing liquid metal which has leaked through the valve seals and returning it to the tank by the pump. The pump chamber is substantially isolated from the liquid metal pool or bath in the tank, whereby the absorption of inert gas into the liquid metal bath is minimized.

Description

United States Patent ubsek et al.

[ 51 Jan. 18, 1972 [54] STORAGE TANK FOR LIQUID METAL [72] lnventors: Frantisek Dubsek; Vaclav Tomes, both of Brno; Mojmir Nlgrin, Jaromer; Jiri Sobotka, Brno, all of Czechoslovakia [73] Assignee: Prvni brnenska strojlrnn, Zavody Klementa Gottwalda narodni podnik, Brno,

Czechoslovakia [22] Filed: Dec. 29, 1969 [21] Appl. No.: 888,369

[52] US. Cl ..l65/l08, 222/385 [51] Int. Cl "F28! 13/06 [58] Field of Search ..222/385; 165/108 3,130,878 4/1964 Zimmermann ..222/385X Primary Examiner-Carroll B. Dority, Jr. Attorney-Arthur 0. Klein [57] ABSTRACT A system for circulating heated liquid metal (e.g. metallic sodium) through a conduit arrangement wherein, for example, the liquid metal functions as a heat-exchanging medium and is alternately cooled and heated. The system includes a unitary liquid metal storing and circulating device having a tank for storing the liquid metal and a pump for circulating the liquid. The pump, which is immersed in the liquid in the tank, has a liquid flow-through bearing and means for removing excess liquid metal which flows through the bearing. Valves associated with the system have liquid metal flow-through seals; means is provided for removing liquid metal which has leaked through the valve seals and returning it to the tank by the pump. The pump chamber is substantially isolated from the liquid metal pool or bath in the tank, whereby the absorption of inert gas into the liquid metal bath is minimized.

12 Claims, 3 Drawing Figures PATENTED JANIBIQTE 3,635,286

SHEET 1 OF 2 Inventor.

Want/56k Du BSEK acln wfik I I"! .Y] 456% ATTORNEY STORAGE TANK FOR LIQUID METAL This invention relates to a system for circulating and storing heated liquid metals. Among the liquid metals which the apparatus of the invention may handle, for example, liquid sodium, although it is not limited thereto. Equipment operating with liquid metals consists generally of a heating surface where liquid metal absorbs heat, and of an area where the liquid metal transfers the heat to another heat carrier, of circulating liquid metal pumps, of liquid metal charging pumps, of flowmeters, of liquid metal piping, of expansion tanks, of liquid metal storage tanks, of liquid metal shutoff and control valves, of liquid metal filtering apparatus, of inert gas distribution system and of cooling liquid distribution system.

In conventional layouts employed in heavy duty service, all the aforesaid elements are separately mounted in boiler houses; this is very disadvantageous from the operational and safety point of view. It is frequently necessary that the area where the liquid metal transfers heat is widely separated from devices which are to be cooled by liquid metal. Such separate location of the pumps, of the valves, of the cleaners and of the liquid metaltanks gives rise to problems in plant equipment operating with liquid metals. Such problems are the removing of the seal leakage of pumps, valves and flanges on the side of the liquid metal and problems relating to the desire to eliminate the spaces in the liquid metal circuit of which full advantage is not taken during the operation. Such spaces include those over the liquid metal level in the expansion and storage tanks. Moreover, the separate location of the aforesaid equipment assemblies for liquid metals complicates the control of the particular equipment and does not insure the safety of its operation.

A liquid-metal-circulating and storing system according to the present invention has as an object the removal of these disadvantages; connected to the liquid metal circuit there is a liquid-metal-circulating pump, which is built into and connected to the tank space by means of a flow-through seal. The liquid metal circuit, in order to take the volume thermal expansion of the charge of the liquid metal circuit, not only has a built-in pump, but also shutoff and control valves. The liquid metal circulating through the pump communicates with the .liquid metal charge in the storage tank by means of a hydrostatic bearing; theliquid metal flowing through the valves communicates with the same charge by'means of a flowthrough seal so that the single seals of the pump and of the valves seal only the pressure of the inert gas whichfills the space over the level of the liquid metal in the storage tank. Liquid metal vented from the liquid metal circuit is introduced to the inert gas space of the storage tank. A liquid metal I cleaner is advantageously connected in parallel with the storage tank. The circulating pump, valves and inlet and delivery piping of the pump are preferably arranged in a section of the storage tank.

The liquid metal absorbs gas at a rate which increases with increasing agitation of the upper surface of the metal. Gas absorption through the upper surface of the liquid metal can be substantially reduced by means of equipment (FIG. 2), the

main feature of which is a separating plate under the upper surface of the liquid metal. Stirring of the liquid metal caused by the pump outlet and inlet takes place only under the separating plate; such stirring is not carried over to the space above the plate.-The liquid metal pump in the tank according to the invention has one shaft bearing situated directly in the liquid metal space. It operates at the temperature corresponding to the ambient temperature of the pumped liquid metal,

. which can, however, in some cases be extremely high and thus may deleteriously affect the bearing material. The working The invention will be further described with reference to the accompanying drawings which are given by way of example and include: I

FIG. 1 is a schematic view in section of a first system in accordance with the invention;

FIG. 2 shows a first variant of the pump in the tank; and

FIG. 3 shows a storage tank with a second variant of the pump.

In the system shown in FIG. 1, a storage tank 1 is connected to a liquid metal circuit 2 by means of discharge or pressure piping 3 and inlet or suction piping 4 connected to a pump 5 which is submerged in the storage tank ll. An upper branch 6 on tank 1 has an extension part 7 secured thereto. The pump 5 is mounted on supporting plate 8 which is sealed to part 7. A hood 9, which encloses an electric motor 10, provides an inert gas space 11 sealed from the surrounding atmosphere. Inert gas space 11 is separated from the inert gas space 12 over the liquid metal level by a seal 14! around vertical pump shaft 15. An impeller 16, secured to the lower end of the pump shaft, is surrounded by a pump casing, as shown. The pump casing is mounted on the lower end of a tube 32 the upper end of which is affixed to plate 8. The liquid metal space within the pump casing selectively communicates with liquid metal space 13 in the storage tank 1 by means of a check and shutoff valve 18 which is selectively operated by a linkage 26 having a control handle 26a. When valve 18 is opened, it permits the pump to suck liquid metal from pool 13 into the pump and thence into the conduit system 2. Liquid metal delivered by pump 5 flows upwardly through conduit 3, through valve 3a within tank extension 7, to the circuit 2 where it flows through a heat-absorbing heat exchanger 34, located at a distance from tank ll. After leaving heat exchanger 34, the cooled liquid metal flows to a metal heating heat exchanger 35 and thence into pump inlet conduit 4 through a valve 19 within tank extension 7.

The lower end of pump shaft 15 is mounted in a flowthrough or hydrostatic bearing 17. Liquid metal which leaks through bearing 17 wells up into tube 32 where it remains as a column in pressure equilibrium.

Inert gas is supplied to the space 12 in tank 1 above the liquid metal 13 by a source 24a of inert gas under pressure, such source being connected to the tank 1 through a conduit 24. The liquid metal circuit 2 is vented by a pipe 23 leading to a crossover fitting 24b and thence to tank 1 through a valve 1% disposed within tank 1. The above-mentioned conduit 24 is connected to the tank l by way of crossover fitting 24b as shown.

A liquid metal cleaner 25 is connected between discharge conduit 3 and the tank 1. Thus, there is an inlet valve 21a disposed within tank extension 7 connected to conduit 3 and an outlet valve 25a disposed within the tank 1 above the liquid metal space 13.

It is to be noted that

valves

20, 20a, 20b, 3a and 25a are mounted within the tank 1, and have valve stems projecting outwardly through and sealed to the walls of the tank. The valves are provided with hand wheels; the hand wheels of

valves

20, 20a and 20b are designated with an added a, whereas the hand wheels are designated with an added I).

The valves 20, 20a and 20!: are provided with flow-through seals 19, 19a and 19b, respectively. The same is true of valves 21a and 25a. Any liquid metal which leaks through the flowthrough seals of all of such five valves falls into the pool 13 of liquid metal and is eventually returned, as the need arises, to the conduit 2 through the valve 18.

In FIG. 2 there is shown an alternative pump arrangement 5 in the storage tank 1 containing liquid metal 13. The suction branch 4} of the pump 5 discharges under the liquid metal level. The pump 5 sucks the liquid metal by suction branch 28 in the form of a shroud and discharges it through the pipe 3 to the circuit 2. A separating plate 27 is situated under the liquid metal level in the storage tank 1. This separating plate 27 prevents the stirring by the pump of the liquid metal above the separating plate 27, and thus prevents the inert gas from being entrained by the liquid metal.

FIG. 3 shows a further variant of the system of the invention. The shaft of pump 5' is mounted with its lower part in an antifriction bearing 29 which operates in the liquid metal 13 at relatively high temperatures. The cooler and purified liquid metal flows in the direction of the arrow from the liquid metal cleaner through the pipe 31 which is situated above the antifriction bearing 29. The liquid metal level in the pipe 32 is higher than level H by a height h. Because of the pressure difference, the cool liquid metal as e.g., sodium is forced through the antifriction (ball) bearing 29, which is thus kept at the lower temperature than is the temperature of the pumped liquid metal 13; the antifriction bearing 29 is preferably protected from corrosion which may be caused by impurities contained in the liquid sodium.

The system in accordance with the invention removes the difficulties relating to the seal leakage of the pump and valves for liquid metals; it removes the problems connected with expansion tanks; it utilizes to better advantage the circulating circuit for the liquid metal. it also utilizes the circulating pump as a feeding pump, improves the processing safety and the controllability of equipment operating with liquid metals, minimizes the absorption of inert gas by the liquid metal surface in the tank, raises the permissible bearing load, and prolongs the service life of the pump impeller bearing.

Although this invention has been illustrated and described with reference to a plurality of embodiments thereof, it is understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

We claim:

1. A system for circulating oxidizable liquid metals through a conduit arrangement, comprising a unitary liquid metal storing and circulating device having a tank liquid metal therein and a pump for circulating the liquid metal, the pump being disposed within the tank and pump discharge and inlet conduits extending to the pump through the walls of the tank, and comprising a source of inert gas, means for introducing said inert gas into the space within the tank above the liquid metal.

2. A system for circulating heated liquids through a conduit arrangement, comprising a unitary liquid storing and circulating device having a tank for storing the liquid and a pump for circulating the liquid, the pump being disposed within the tank and pump discharge and inlet conduits extending to the pump through the walls of the tank, the pump being immersed in the liquid, the pump having a pump shaft supported in a liquid flow-through bearing, and means supplying liquid of lower than ambient temperature to the bearing.

3. A system for circulating heated liquids through a conduit arrangement, comprising a unitary liquid storing and circulating device having a tank for storing the liquid and a pump for circulating the liquid, the pump being disposed within the tank and pump discharge and inlet conduits extending to the pump through the walls of the tank, the pump being immersed in the liquid in the tank, a horizontal plate separating the space within the tank to an upper and a lower space, a pump inlet means communicating with the lower space, and said inlet conduit communicating with said lower space, whereby the liquid in the upper space is protected from being stirred by the action of the pump.

4. A closed pressure system for circulating liquid metal comprising a unitary liquid metal storing and circulating device having a tank containing liquid metal, means to introduce inert gas into the tank and provide an inert atmosphere in the tank in the space above the liquid metal therein, a conduit arrangement, a pump disposed within the tank and serving to feed liquid metal to the conduit arrangement as well as to circulate liquid metal therethrough, the conduit arrangement including pump discharge and inlet conduits extending to the pump through the walls of the tank.

5. A system according to claim 4, comprising pump feeding conduit means communicating with the liquid metal in the tank, discharge and return conduit means, and valves within the tank interposed in said discharge and return conduit means so that t e liquid metal leaking through the seals of the valves drips into the tank.

6. A system according to claim 4, wherein the pump is immersed in the liquid metal, and the pump has a pump shaft supported in a liquid flow-through bearing to which cooler liquid metal is supplied through a separate conduit from a filter device connected in parallel with the tank, whereby the liquid metal flowing through the bearing has the impurities removed therefrom in the filter device, whereby to prevent the bearing from corrosion.

7. A system according to claim 4, comprising piping connected to the outer conduit arrangement and leading to the tank for venting the outer conduit arrangement, whereby the tank may be used as a venting and an equalizing tank.

8. A system according to claim 1, comprising control, shutoff and safety valves interposed in the conduit arrangement, said valves being disposed within the tank and having valve spindles which pass through the walls of the storage tank and are sealed thereto by means sealing against the escape of inert gas.

9. A system according to claim 8, comprising means for removing liquid which leaks from the valves and returning it to the pump.

10. A system according to claim 8, comprising an upstanding section of the tank above the liquid pool therein, and wherein delivery and inlet valves in the conduits in the tank are disposed in said upstanding section.

11. A system according to claim 10, comprising a depending section of the tank in alignment with the upstanding section, the pump being disposed in said depending section and immersed in liquid therein.

12. A system according to claim 2, wherein the bearing is disposed at the top of the pump, comprising a vertical tube surrounding the bearing and isolating it from the liquid in the pool in the tank and means for introducing said cooler liquid into the tube.

a a a a:

Claims

5. A system according to claim 4, comprising pump feeding conduit means communicating with the liquid metal in the tank, discharge and return conduit means, and valves within the tank interposed in said discharge and return conduit means so that the liquid metal leaking through the seals of the valves drips into the tank.